Data from ESA’s Gaia spacecraft indicate a large galaxy collided with the Milky Way about 10 billion years ago, leaving identifiable stars strewn in its wake to help astronomers piece together our galaxy’s history.

A head-on collision between the Milky Way and a smaller body dubbed the “Sausage” galaxy eight to 10 billion years ago had a profound effect on the structure and evolution of Earth’s home in space, astronomers say.

The second data release from the European Space Agency’s hard-working Gaia spacecraft reveals the position and brightness of nearly 1.7 billion stars in the most detailed star catalogue ever developed.

Australian astronomers are in the process of collecting the spectra of a million stars across the Milky Way in a project to study galactic evolution. In the process, they hope to track down at least some of the sun’s lost siblings.